ALIy ABOUT AI^FALFA. 347 



during June. Cool weather checks the dying until the 

 next June, when a ring of alfalfa dies on the margin 

 of the circle. Its annual spreading indicates a fungous 

 trouble. The disease spreads slowly, about fifty feet 

 each year, and its advance is not stopped by plowing 

 around the diseased spots. Hence the fungus must 

 attack the healthy plants for some time before there 

 are any visible signs of disease. The disease attacks 

 the crown and upper portion of the root, no fungus 

 being found below sixteen inches from the surface. 

 The fungus is identical with the cotton-root rot. Salt, 

 kerosene, and other remedies have been found to be 

 partially effedlive, but no sure cure or preventive has 

 yet been found. 



In other humid climates some farmers have found 

 that the plant is affe(5led with leaf spot. This disease 

 is found in nearly every place where alfalfa is grown 

 in the moist Atlantic states. Usually it does not attack 

 the plant until the second year's growth, when the 

 plant is able to survive the disease. Sometimes, how- 

 ever, it completely destroys seedling plants. The 

 disease shows itself as minute dark-brown spots of 

 irregular shape upon the green or discolored leaflet. 

 The center of each spot forms a pustule. In this are 

 developed the spores, which are set free by the break- 

 ing of the epidermis. The disease readily survives the 

 winter, and may develop year after year in the same 

 field. In serious cases, covering with straw and burn- 

 ing will stop the disease. It may be held in check by 

 frequent cuttings. 



Dodder is an enemy that has given alfalfa more or 

 less trouble out west. It is a small annual parasitic 



